Yeast respiration with different sugars

Stanley90

Can't find any info anywhere on why glucose is faster than fructose for aerobic respiration of yeast..

Reply 1

helloeverybody

Stanley90

Can't find any info anywhere on why glucose is faster than fructose for aerobic respiration of yeast..

I think and i could be wrong is that yeast have better adapted enzymes to hydrolyse glucose rather than fructose, but that is a stupid question or prehaps its even to do with the location of the glycosidic bond. glucose 1,4 and fructose 1,2. but im only guessing

Reply 2

Stanley90

yeah it is something to do with that and the thing is scientists don't know definitively either so how is an A level student meant to know :/

thanks for the reply btw

anyone?

Well if this is courswork i'm doing the same although i guess your deadline would have passed, i've been told its just that glucose fits the shape of the enzymes used by yeast for respiration better

: )

Reply 5

ixivxivi

Hmmm, well, in mammals, the breakdown of fructose (first step = glycolysis) is reasonably similar to that of glucose. If the enzyme hexokinase is present (as it is in muscle tissue), fructose can be phosphorylated to give fructose 6-phosphate, which is 2 steps into glycolysis from glucose (ie the fructose reaches this with only 1 step, glucose with 2), so from that you'd think that fructose breakdown might be mildly faster. In cells not containing hexokinase (such as liver cells, which contain glucokinase, which only phosphorylates glucose), the fructose has to unter go a more complex route to enter glycolysis, however, it only undergoes 3 steps to get there, rather than the 4 of glucose glycolysis.

So perhaps that's not the best path to argue down, considering I'm talking about the wrong species AND get the wrong out come :P:

May google, although as the above poster says, I'm sure you no longer care :smile:

Reply 6

mchard2

Glucose is faster as it does not have to be brocken down to be used during the reaction, where as surcose and maltose must be brocken down. Yeast must activate a gene for the production of the enzyme to break down surcose and maltose, that is why sucrose and maltose take longer!!